Playground Physics

The Physics on a Playground

With slides, swings and seesaws, the playground is a great place to observe physics. 

Physics of Swings:

Being on a swing is a great example of both potential and kinetic energy. Swings work by converting potential energy into kinetic energy, then kinetic energy back into potential energy, over and over again.

You convert the kinetic energy to potential energy by pumping your legs. When someone is at the max height it will have the most potential energy. When the swing is at its minimum height, there is no potential energy and all kinetic energy.

Even though you’re not moving at the very top of each swing, you can think of your height as your potential for speed. A physicist would say that your kinetic energy–that is, your speed–is “stored” as potential energy at the top of each swing.
More height is more speed, just waiting to happen.

You can increase the energy in two different ways. If someone pushes you, that increases kinetic energy. Or you can increase your potential energy by pumping your legs. By raising your legs, you can increase your overall center of mass and this raises the height of each swing which increases the potential energy.

Physics of  a Seesaw:
A seesaw is an example of a lever. The fulcrum/pivot point is the part of the lever that does not move, its in the middle.  The resistance, or the downwards force, is the weight of the person you are trying to lift is at one end.

The work, force applied to the lever, is the person sitting on the other end of the seesaw. The force that is applied by pushing down/pushing up on one end of the seesaw can substitue for the mass on the other end.  The longer the lever, the less force one needs to lift a heavy object.

The mechanical advantage of using a long lever to lift a heavy weight is

apparent: much less force is need to lift a heavy object with a lever if the distance
from the pivot point is large compared to the distance of the heavy object from the
pivot point.

By moving the from point or adjusting the distance between the two people, you can get the seesaw to be balanced. 

Physics of Slides: 

A slider will have three forces acting on them. The force of the slide, the force of gravity and the force of friction. Technically, both the force from the slide and the frictional force are forces the slide exert on the slider. Typically, the vertical one is called the normal force. As the slider slides, the acceleration in the vertical direction is zero. This means that the net force in the vertical direction must also be zero. 

Earth's gravitational force pulls the rider down the slide. Friction decreases the speed of the rider's descent. Newton's first law of motion states that the rider will remain at the top of the slide until disrupted by another force, such as a push. The rider is an example of potential energy when positioned at the top of the slide. When the rider slides down the slide, they are an example of kinetic energy

Sources:
https://indianapublicmedia.org/amomentofscience/swinging-physics/
http://ffden-2.phys.uaf.edu/212_spring2011.web.dir/Samantha_Porreca/Seesaw.html